Electrochemical analytical sensors are commonly used to determine the presence and concentration of a biological analyte. Such sensors are used, for example, to monitor blood glucose levels in diabetic patients.
Although many currently available sensor strip products require relatively large sample volumes, e.g., generally requiring 3 μL or more of blood or other biological fluid, there has been a trend for small volume sizes, such as 1 μL and less. For example, U.S. Pat. Nos. 6,143,164, 6,338,790 and 6,616,819 provide various configurations of small volume (i.e., less than 1 μL), disposable sensors. These patents suggest that sensors with sample chamber volumes of 0.5 μL, 0.25 μL, and even 0.1 μL can be made.
However, as the volume of sample chambers in the sensors decreases, it becomes increasingly more difficult to fill the sample chamber with an accurate amount of the sample to be analyzed, in part due to the small area available through which the sample enters. Additionally, as the sample chamber volume decreases, there is increased difficulty in repeatedly manufacturing the small volume sample chamber.
As electrochemical sensors continue to be used, there continues to be an interest in electrochemical sensors that utilize a small sample volume of biological fluid for analysis.